Weather-proof coating for rubber



' reviewing."

' issu o. WITHER sews, or enn'GEwooD, MARYLAND, AND ARTHUR F; sQWASHINGTON, nrsrmororconuivmm I wEArrrE -rnoor :oosrius'rou RUBBER f vs vliqmi iea m mes nee'ember 16', 1929. serial N s .'414;s1s."

, (GRANTED unnsurnii Aer or union 3, 1883;AS1'AMENDED Artur. so; 1928;2,70 0. e. 757

{This seventies Hearted been, mayrbe manufactured a-nd u'sed byior forthe Gov ernjment -for Government purposes, without th Paym tel ofen ir ytyi t r eng 4 This invention'relatesin generalto' coatlng 1 compositionsand more particularly has refer.-

ence to a protecti've: coating for rubber. J

. f-Previous Ito, tl1istiine,]1it fhas been qwell known vthat if 7 rawor vulczm ized rubber is e st'retched 'orcompressedfeven slightly and isexposed to the air,particularlyjunder chang V I ingiclimatic,'jconditioris, rapid deterioration :Ew'illj: follow. This i'sooo isionedbyfthe fact fthat the ordinaifyslow deteriorating eilecttions of theinterior of the bodvofrubber. Itwill be appreciated thatanygcoating or 'filn jwhic h willprevent"theiaccess ofair toorubbenwill. inhibit jthe. 'deterioration er the same; iPr ior-tothistime howevenit has been diflicult'to provide; animpermeable fi m for,coating sufliciently elastic to :eli'ectively adg hereto rubberwhiichiis fl" el l lentlfv"or con v H tinu-ouslysubjected todistortion.e

caused by the'action. of; oxygen" is enormously, accelerated-by reasonof theexposure of por-.

restrictions set forth. r j a e We have found that coatings orfilmsf-derived by dissolving raw rubber and nitroe 1i cellulosein'a-rnixture of solvents such as .ran yljacetate, and benzene, whenappliedto p H rubber are sufliciently flexible 'to withstand Q,considerabledistortionwithout cracking and s I I breaking, and ithat thesame is practically;

gen and light.

BEALLOF While we Set: forth our objects and outlined the essence of ourinvention, the-;w i H same cons sts partlcularly '1n the mgre'dlents andproportions to be hereinafter set forth and: clairned, with theunderstanding that the severalynecessary substances and corn -T vpounds-comprising our, invention \maybe I o 'tureandfapplioation oil thesame carried out? under; differentlcond tions, the part cular varie dwithin wide proportions and the mixe coating specified andmannerofapplication! being described as an example of carrying s e the inventioninto practical effect, without limiting the improvements to theparticular I impermeable to air. V'Paraflin wax has been I An objectofthislinventioniis to provide p I I demonstrated to improve thecoatingQcomQ composition. which willj afiord, an effective position,"andit has'also been found thatfa protectivecoating'forrubberl'1 v dye and-an .anti-oxidant.rnay be added to p Another object 'of thisinventionistoprm advantage. Nitrocellulose and raw rubber- O vide acompositionwhichirnay be applied to may be brought into the solutionbyghexav eitherfrawjor vulcanized rubber to 'afi'ord a lineor hexalineacetate; butran insuflicient; I

'prgt'ective coating therefor; i j amount in solution is obtained tomake itof till practical use. p e a "In practicing our invention, wehaverfound that a-desirable manner of obtaining a'suitable solutionconsists essentially of dissolv- I ing paraflin wax in rubbercementbywarrning to-approxiinately 50 CL, and adding another objectofthisinvention is to 'providea protective coating for rubber which willnotcrack on or separate therefrom when r the rubber is flexed orstretched under ordinar'y usage. 1 I I 1 I A furtherobjectofthisinvention is to pro- -teristics of benzene, and applying theresult- 50 ing cornposition torubber" goods for protec- 1vide a mixedsolvent'for dissolving raw rub nitrocellulose lacquer. The proportion ofthe d solvent mixture may then be aded with con-g tinuous stirring untila clear solution results. I If a dye or anti-oxidant, or both, is deemed"desirable,this is preferably added to the final solution. f Particularadvantages of this coatingover certain other coatingsicontaining rubberandcarbon'black in suspension along with other ingredientsis'particularlyfthat' the solid colors are all in solution andthat thecoatingmay be made practically color lessor of any dealaten]: bytheaddition of a suitable dye.

.n will be manifest that a solution oftliis kind has the distinctadvantage of producing atrue on the; surface oithe rubber on which it"is appliechwhich feature is" lacking the application of'a coatingcontaining materials in suspension. 7

As examplesof the'mat eri ls contained in our solution, we have mixed"approximately" 7 42% of raw rubber, 28% of nitrocellulose,

% of pa-raiiin wax, and dissolved the same in a mixture of approximatelyof .amyl acetate and 60% benzene to a concentration of approximately614%.: of solids; (Di'therzpro-iiportions of the same, solid ingredientscanbe use'dfas for instance 6% ofraw'rubber, 10%

' of nitrocellulose and 84% of parafiin wax dis.

solved in the; sameproportions of benzene and amyl acetate; to, form aconcentration of approximately 8%- of solids.

' has been found, however, that-the decrease in amount of raw rubber andnitro "celfliilose and the addition of paraili'n over "certainflimitsdoes not afford as. eiii'cient pro tection' toth-erubber and isnot asflexible or "elastic; The addition ofsm'al-l-"amounts' 'of conninercialanti-oxid'ants and dyes m the -'sol;ut1o r increases: the protectivequa-llti'es of the coating to om extent. if thesegniaterials: are added,'with reference to the proportions mentioned-in the first solution, 7410% of raw rubber will'be u'sedaand l% each 'of theanti-oxidantandtlye, or either may be t-nnployed alone, increasing thepercentage or the rubberfby one percent. These percent- I Yages na-y,1ofcourse, be varied to suit the 1 particular requirements,Sucliantioxida-nts asfstabili-ternay be m io dgana dyes, for instance,of the characterof soudanred used." v r Concentrations of thesesolutions as well niu-1n concentration obtainable with such solids" asamyl acetate and benzene'im-i-xtures centrations are attempted, eitherone or the other of the ingredients precipitates from as 4% of solids'may be used, but the ma-xi is; approximately 10%". *VVhen' higher C011the solution.

bodiment of our invention, wewish itto be understood that. we do notconfine ourselves. i

entthat changes and variations may be made, therein by those skilled inthe art 'without departing' from the spirit of the ini vention, or;vexceeding the scope oi-"the iap V I pended claims. J VVeclaim a;

1. A protective coating composition for 7 rubber comprisingapproximately 42% V raw rubber, 28% nitrocellulose and 30% parafiindissolved in a suitable solvent.

22' A protective coating composition for to the precise steps oringredients hereinset forth, by way ofexplanation, as it is apparrubbercomprising approximately, 42% raw rubber, 2'8, nitrocelihl-lose and 5arafiin dissolved' in a mixedsolution of arriy-l? acetate and benzene.

. A protective coating composition for rubber comprising approximately42% raw frubb'er,28% nitrocellulose and 30% paraflin d liI-IiXedsOIuti-Qn g i of a et t benzene; I ,v V

- 4. A protectiye' coating composition for rubber comprisingapproximately 40% raw rubber, 2'8%- nitrocellulose, 30% paraffin, 1% dyeand 1% anti-oxidant, dissolved in a mixed solution consisting ofapproximately 40%amyl acetate and'60% benzene. 5'. A protectivefcoatingcomposition for rubber comprising a quantity Da um- 1111,

lose, a larger quantity of paraliin, a' still larger quantity of rawrubber, I and a-isinall amount of a dye and an -anti-oxid ant," saidmaterial'sbelng dissolved inasolvent formed of amyl acetateand benZineQI In testimony whereof" We aiiix our signatures.

, ARTHUR 'F.,BEAL,' V

'The coating may 15$ applied either" by brushing or by dipping therubber to be treated in the solution. ,Va-rioustypesof VlllCtiIllZQClrubber treated with four applications of the preferred solution by meansof 7 brush and by dipping and allowed to stand tor twenty-four hourstill thev coating: was

' thoroughly dry have been bent double. and 1 stretched approximately 5%and exposed to 1 the: weather in this condition. Such-samples were foundto withstand deterioration from four to twenty times as longas',controlled samples. exposed under the same conditions.

Thereis accomplished by this invention a coating composition for rubberfor protection against. the:cleterioratingaction of light and .7

SAMUEL o. wrrnnnsroon.

